Add method to return non-proxied URLs

Uses string interpolation to get around the proxy rewriting the URLs.

src/config/shim.js

@@ -84,3 +84,29 @@
     bodyEl.classList.add('is-proxied');
   }
 })();
+
+/**
+ * Use a list of canonical URLs that might be changed by a proxy server, detect any
+ * changes, and return the correct canonical URL.
+ */
+window.getCanonicalUrl = () => {
+  const canonicalUrlPattern = /^https:\/\/(ui|qa|dev|devui)\.adsabs\.harvard\.edu$/;
+
+  // URLs that could be rewritten by the proxy server
+  const couldChangeUrls = [
+    { env: 'ui', url: 'https://ui.adsabs.harvard.edu' },
+    { env: 'qa', url: 'https://qa.adsabs.harvard.edu' },
+    { env: 'dev', url: 'https://dev.adsabs.harvard.edu' },
+    { env: 'devui', url: 'https://devui.adsabs.harvard.edu' },
+  ];
+
+  const [changedUrl] = couldChangeUrls.filter(
+    ({ url }) => !canonicalUrlPattern.test(url)
+  );
+
+  // if we detect a change in one of the URLs, return an interpolated string to keep from getting rewritten
+  if (typeof changedUrl !== 'undefined') {
+    return `https://${[changedUrl.env, 'adsabs', 'harvard', 'edu'].join('.')}`;
+  }
+  return `https://${['ui', 'adsabs', 'harvard', 'edu'].join('.')}`;
+};

src/js/apps/discovery/main.js

@@ -170,13 +170,14 @@ define(['config/discovery.config', 'module'], function(config, module) {
 
           // check for is-proxied class, and if present, send alert
           if ($('body').hasClass('is-proxied')) {
+            const url = window.getCanonicalUrl();
             const msg = `
               <p>
                 You are using a proxied version of ADS, we recommend you switch to the regular non-proxied URL: 
-                <a href="https://ui.adsabs.harvard.edu${location.pathname}" rel="noopener noreferrer">https://ui.adsabs.harvard.edu</a></p>
+                <a href="${url}${location.pathname}" rel="noopener noreferrer">${url}</a></p>
               <p>
                 Configure authenticated access to publisher content via the Library Link Server in your account  
-                <a href="https://ui.adsabs.harvard.edu/user/settings/librarylink" rel="noopener noreferrer">preferences</a>.
+                <a href="${url}/user/settings/librarylink" rel="noopener noreferrer">preferences</a>.
               </p>
             `;